Index: class-wp-media-list-table.php
===================================================================
--- class-wp-media-list-table.php	(revision 30041)
+++ class-wp-media-list-table.php	(working copy)
@@ -70,7 +70,7 @@
 			if ( !empty( $_GET['attachment-filter'] ) && strpos( $_GET['attachment-filter'], 'post_mime_type:' ) === 0 && wp_match_mime_types( $mime_type, str_replace( 'post_mime_type:', '', $_GET['attachment-filter'] ) ) )
 				$selected = ' selected="selected"';
 			if ( !empty( $num_posts[$mime_type] ) )
-				$type_links[$mime_type] = '<option value="post_mime_type:' . urlencode( $mime_type ) . '"' . $selected . '>' . sprintf( translate_nooped_plural( $label[2], $num_posts[$mime_type] ), number_format_i18n( $num_posts[$mime_type] )) . '</option>';
+				$type_links[$mime_type] = '<option value="post_mime_type:' . sanitize_mime_type( $mime_type ) . '"' . $selected . '>' . sprintf( translate_nooped_plural( $label[2], $num_posts[$mime_type] ), number_format_i18n( $num_posts[$mime_type] )) . '</option>';
 		}
 		$type_links['detached'] = '<option value="detached"' . ( $this->detached ? ' selected="selected"' : '' ) . '>' . sprintf( _nx( 'Unattached (%s)', 'Unattached (%s)', $total_orphans, 'detached files' ), number_format_i18n( $total_orphans ) ) . '</option>';